U.S. patent number 9,944,567 [Application Number 15/150,546] was granted by the patent office on 2018-04-17 for method of inhibiting irregular aggregation of nanosized powder.
This patent grant is currently assigned to NATIONAL CHUNG SHAN INSTITUTE OF SCIENCE AND TECHNOLOGY. The grantee listed for this patent is NATIONAL CHUNG SHAN INSTITUTE OF SCIENCE AND TECHNOLOGY. Invention is credited to Li-Jiuan Chen, Yen-Chung Chen, Hong-Fang Huang, Yu-Chun Wu.
United States Patent |
9,944,567 |
Chen , et al. |
April 17, 2018 |
Method of inhibiting irregular aggregation of nanosized powder
Abstract
A method of inhibiting an irregular aggregation of a nanosized
powder includes (A) providing a nanosized ceramic powder to perform
thereon a thermal analysis and thereby attain an endothermic peak
temperature; (B) performing an impurity-removal heat treatment on
the nanosized ceramic powder at a temperature higher than the
endothermic peak temperature; (C) switching the nanosized ceramic
powder from a temperature environment of the impurity-removal heat
treatment to an environment of a temperature higher than a phase
change temperature of the nanosized ceramic powder, followed by
performing a calcination heat treatment on the nanosized ceramic
powder in the environment of the temperature higher than the phase
change temperature of the nanosized ceramic powder, wherein the
nanosized ceramic powder skips the temperature environment between
impurity-removal heat treatment and calcination heat treatment to
shun generating a vermicular structure, avoid crystalline
irregularity and abnormal growth, reduce particle aggregation, and
achieve satisfactory distribution.
Inventors: |
Chen; Li-Jiuan (Taoyuan,
TW), Chen; Yen-Chung (Taoyuan, TW), Huang;
Hong-Fang (Taoyuan, TW), Wu; Yu-Chun (Taoyuan,
TW) |
Applicant: |
Name |
City |
State |
Country |
Type |
NATIONAL CHUNG SHAN INSTITUTE OF SCIENCE AND TECHNOLOGY |
Taoyuan |
N/A |
TW |
|
|
Assignee: |
NATIONAL CHUNG SHAN INSTITUTE OF
SCIENCE AND TECHNOLOGY (TW)
|
Family
ID: |
60295047 |
Appl.
No.: |
15/150,546 |
Filed: |
May 10, 2016 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20170327426 A1 |
Nov 16, 2017 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C04B
35/62645 (20130101); C04B 35/44 (20130101); C04B
35/622 (20130101); C04B 41/80 (20130101); C01F
17/34 (20200101); C01P 2002/72 (20130101); C04B
2235/5454 (20130101); C01P 2004/03 (20130101); C04B
2235/72 (20130101); C04B 2235/81 (20130101); C04B
2235/3224 (20130101); C04B 2235/764 (20130101); C01P
2004/62 (20130101); C01P 2002/88 (20130101); C04B
2235/3217 (20130101); C04B 2235/3225 (20130101) |
Current International
Class: |
C04B
41/80 (20060101); C04B 35/44 (20060101) |
Other References
Palmero, Paola, et al. "Effect of heating rate on phase and
microstructural evolution during pressureless sintering of a
nanostructured transition alumina." International Journal of
applied ceramic technology 6.3 (2009): 420-430. cited by examiner
.
Tartaj, Jesus, et al. "Sol-gel Cyclic Self-Production of
.alpha.-Al2O3 Nanoseeds as a Convenient Route for the Low Cost
Preparation of Dense Submicronic Alumina Sintered Monoliths."
Advanced Engineering Materials 4.1-2 (2002): 17-21. cited by
examiner.
|
Primary Examiner: Rump; Richard M
Attorney, Agent or Firm: Schmeiser, Olsen & Watts,
LLP
Claims
What is claimed is:
1. A method of inhibiting an irregular aggregation of a nanosized
powder, the method comprising the steps of: (A) providing a
nanosized ceramic powder to perform thereon a thermal analysis and
thereby attain an endothermic peak temperature; (B) performing an
impurity-removal heat treatment on the nanosized ceramic powder at
a temperature higher than the endothermic peak temperature; (C)
switching the nanosized ceramic powder from a temperature
environment of the impurity-removal heat treatment to an
environment of a temperature higher than a phase change temperature
of the nanosized ceramic powder, followed by performing a
calcination heat treatment on the nanosized ceramic powder in the
environment of the temperature higher than the phase change
temperature of the nanosized ceramic powder, wherein the nanosized
ceramic powder skips the temperature environment between the
impurity-removal heat treatment and the calcination heat treatment
to shun generating a vermicular structure.
2. The method of claim 1, wherein the thermal analysis is
differential thermal analysis (DTA)/thermogravimetric analysis
(TG).
3. The method of claim 1, wherein the nanosized ceramic powder is a
Nd:YAG powder.
4. The method of claim 3, wherein the nanosized ceramic powder is
prepared by the steps of: (a) mixing an ammonium bicarbonate
aqueous solution and a Nd:YAG precursor solution to produce a
precipitate of the Nd:YAG powder; (b) obtaining the Nd:YAG powder
by a centrifugal process, followed by rinsing the Nd:YAG powder
with alcohol; (c) placing the Nd:YAG powder in an oven for
drying.
5. The method of claim 4, wherein the Nd:YAG precursor solution is
prepared by dissolving an aluminium nitrate, a yttrium nitrate and
a neodymium nitrate in deionized water.
6. The method of claim 4, wherein the endothermic peak temperature
is 250.degree. C.
7. The method of claim 4, wherein the impurity-removal heat
treatment occurs at 250-350.degree. C.
8. The method of claim 4, wherein the calcination heat treatment
occurs at 1200-1400.degree. C.
9. The method of claim 8, wherein the calcination heat treatment
occurs at 1200.degree. C.
Description
FIELD OF THE INVENTION
The present invention relates to methods of preparing nanosized
powder and, more particularly, to a method of inhibiting an
irregular aggregation of nanosized powder.
BACKGROUND OF THE INVENTION
It is difficult for nanosized ceramic powder of a particle diameter
of 100-500 nm to be well distributed and appropriately sintered,
because a conventional solid-state reaction route is much
constrained by the quality of starting materials. Agglomeration or
uneven distribution of particle diameters of starting nanosized
powder materials necessitates additional processing steps which
precede whatever starting material-based steps. Furthermore, due to
low diffusion coefficients of solid-state substances, nanosized
powder produced by the solid-state reaction route cannot exist in a
pure phase unless it is processed at a relatively high heat
treatment temperature. However, when carried out at a high
temperature for a long period of time, heat treatment leads to
vermicular aggregation among crystallites--an intractable problem
that confronts nanosized ceramic powder preparation processes
nowadays. For instance, pure-phase YAG particles in nanosized
powder can be synthesized by a conventional solid-state reaction
route only at a relatively high heat treatment temperature
(>1600.degree. C.) and, unfavorably, on condition that the YAG
particle diameters are often larger than 1 .mu.m.
YAG nanosized powder can also be produced by a sol-gel process and,
favorably, at a relatively low temperature, say less than
700.degree. C., directly from an amorphous substance through
crystallization. However, the sol-gel process requires a subsequent
heat treatment process. Likewise, YAG nanosized powder can also be
produced by a hydrothermal method which, apart from the aforesaid
heat treatment process, requires a high pressure process and
thereby is restrained by supercritical conditions of water.
Chemical coprecipitation, which is often used to synthesize YAG
powder, entails coprecipitating highly soluble Y and Al, such as
YNO.sub.3 and AlNO.sub.3, with a precipitant to produce a
solid-state precipitate, and then the solid-state precipitate
undergoes a heat treatment process to produce aYAG starting powder.
Advantages of chemical coprecipitation include: Y, Al and Nd ions
are uniformly distributed to an atomic level, YAG phase structure
is directly formed in an amorphous state, usually greatly
decreasing the temperature required for crystallization, and
precluding a transition phase, such as the formation of YAP
(YAlO.sub.3) or YAM (Y.sub.4Al.sub.2O.sub.9), but its YAG powder
particle diameter is small and thus have to undergo a calcination
process to allow the crystal to grow from 50 nm to 220 nm. However,
aggregation among the crystals increases with the calcination
temperature. Hence, the sintering density is compromised.
Hence, manufacturers nowadays deem it important to provide a method
of inhibiting an irregular aggregation of a nanosized powder to
thereafter process nanosized powders (starting materials) produced
by different process techniques so as to enhance process efficiency
and nanosized powder crystal quality, and avoid crystalline
irregularity and abnormal growth, such as overlapping and prepare a
nanosized powder that features reduced particle aggregation and
satisfactory distribution.
SUMMARY OF THE INVENTION
In view of the aforesaid drawbacks of the prior art, it is an
objective of the present invention to provide a method of
inhibiting an irregular aggregation of a nanosized powder,
integrate a nanosized ceramic powder, a thermal analysis, an
endothermic peak temperature, a preheat treatment and a calcination
heat treatment, efficiently prevent powder aggregation which might
otherwise occur during a heating process, and produce a nanosized
powder which features satisfactory distribution and a microscale
size.
Preparation of a compact nanosized ceramic powder requires giving
considerations to the sintering activity of the powder. The
sintering activity of the powder mostly depends on the size, shape,
particle diameter distribution, chemical ingredients, agglomeration
degree, and purity of the powder, wherein the reduction of
particulate size and the enhancement of powder uniformity is
effective in enhancing the sintering activity of the powder.
However, the reduction of powder size readily leads to
agglomeration and reduced powder uniformity. Hence, the sintering
activity has to strike a balance between size and uniformity to
allow the optimal sintering activity to take place in the event of
a specific particulate size. Hence, given technical improvement in
powder uniformity, not only does the optimal particulate size
corresponding to the optimal sintering activity decreases, but the
sintering activity also increases.
In order to achieve the above and other objectives, the present
invention provides a method of inhibiting an irregular aggregation
of nanosized powder, comprising the steps of: (A) providing a
nanosized ceramic powder to perform thereon a thermal analysis and
thereby attain an endothermic peak temperature; (B) performing an
impurity-removal heat treatment on the nanosized ceramic powder at
a temperature higher than the endothermic peak temperature; (C)
switching the nanosized ceramic powder from a temperature
environment of the impurity-removal heat treatment to an
environment of a temperature higher than a phase change temperature
of the nanosized ceramic powder, followed by performing a
calcination heat treatment on the nanosized ceramic powder in the
environment of the temperature higher than the phase change
temperature of the nanosized ceramic powder, wherein the nanosized
ceramic powder skips the temperature environment between the
impurity-removal heat treatment and the calcination heat treatment
to shun generating a vermicular structure.
The thermal analysis is differential thermal analysis
(DTA)/thermogravimetric analysis (TG) intended to gain insight into
the thermal behavior of starting nanosized powder. With the DTA
curve, it is feasible to identify the location of the endothermic
peak and its temperature (endothermic peak temperature). Hence, the
temperature at which the chemical residues of nanosized ceramic
powder (starting nanosized powder) decompose is estimated by
inference, so as to identify the related processing
temperature.
In step (A), the nanosized ceramic powder is a Nd:YAG powder
prepared by following the steps of: (a) mixing an ammonium
bicarbonate aqueous solution and a Nd:YAG precursor solution to
produce a precipitate of the Nd:YAG powder, wherein the Nd:YAG
precursor solution is prepared by dissolving an aluminium nitrate,
a yttrium nitrate and a neodymium nitrate in deionized water; (b)
obtaining the Nd:YAG powder by a centrifugal process, followed by
rinsing the Nd:YAG powder with alcohol; and (c) placing the Nd:YAG
powder in an oven for drying.
According to the present invention, when the nanosized ceramic
powder is a Nd:YAG powder, the Nd:YAG powder (starting nanosized
powder) is analyzed by DTA/TG to thereby determine that the
endothermic peak temperature is 250.degree. C. approximately and
that the phase change temperature is above 1100.degree. C. Hence,
the range of the process temperature of the impurity-removal heat
treatment in step (B) is 250-350.degree. C., whereas the range of
the process temperature of the calcination heat treatment in step
(C) is 1200-1400.degree. C. Alternatively, the calcination heat
treatment is performed on Nd:YAG powder (starting nanosized powder)
at 1200.degree. C. or so.
The above overview and the description below as well as the
accompanying drawings aim to further explain the techniques and
means used to achieve the intended objectives of the present
invention and the effects thereof. The other objectives and
advantages of the present invention are illustrated with the
accompanying drawings and described below.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of the process flow of a method of
inhibiting an irregular aggregation of nanosized powder according
to the present invention;
FIG. 2 is a graph of DTA/TG of a nanosized YAG powder of the
present invention;
FIG. 3 shows SEM pictures of the nanosized YAG powder calcinated at
1200.degree. C. (picture a) and 1400.degree. C. (picture b)
according to the present invention;
FIG. 4 is a graph of the distribution of particle diameters of the
nanosized YAG powder calcinated according to the present
invention;
FIG. 5 is an XRD spectrum of a powder sample obtained by
calcinating the nanosized YAG powder at 900-1200.degree. C. for one
hour according to the present invention;
FIG. 6 shows SEM pictures of a powder sample of the nanosized YAG
powder kept at 1100.degree. C. and 1200.degree. C. for one hour
according to the present invention, respectively;
FIG. 7 is an XRD spectrum of a coprecipitation product calcinated
at 1400.degree. C. for 15-60 minutes according to the present
invention; and
FIG. 8 shows SEM pictures of a powder which did not undergo an
impurity-removing process but underwent calcination at 1400.degree.
C. for 15 minutes (picture a), 30 minutes (picture b) and 60
minutes (picture c) according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The implementation of the present invention is hereunder
illustrated with specific embodiments to allow persons skilled in
the art to gain insight into the advantages and benefits of the
present invention with reference to the disclosure of the
specification.
Preparation of compact transparent YAG ceramics requires giving
considerations to sintering activity of a powder. The sintering
activity of a powder depends mostly on the size, shape,
distribution of particle diameters, chemical ingredients, degree of
agglomeration, and purity of the powder. The sintering activity of
a powder can be effectively enhanced by decreasing the particulate
size of the powder and increasing the uniformity of the powder.
However, decreasing the particulate size of a powder leads to
agglomeration and reduces the uniformity of the powder. The
sintering activity is optimized by striking a balance between
particulate size and uniformity. As a result, maximum sintering
activity is restricted to a specific particulate size. In view of
this, the optimal particulate size corresponding to the optimal
sintering activity will decrease, and the sintering activity will
increase, as a result of any technical improvement in powder
uniformity.
The prior art usually focuses on the preparation of nanosized
powder either to the detriment of the appropriateness of nanosized
powder size or to lead to powder aggregation. By contrast, the
present invention teaches analyzing the characteristics of a powder
with fundamental thermal analysis curves to thereby identify an
appropriate temperature process interval, then eliminate the
impurity phase left on the interface under a low-temperature
process condition, and finally effectuate phase change and crystal
growth rapidly at high temperature during a short period of time,
so as to avoid crystalline irregularity and abnormal growth, such
as overlapping and prepare a nanosized powder that features reduced
particle aggregation and satisfactory distribution.
Referring to FIG. 1, there is shown a schematic view of the process
flow of a method of inhibiting an irregular aggregation of
nanosized powder according to the present invention. As shown in
the diagram, the method of inhibiting an irregular aggregation of
nanosized powder comprises the steps of: (A) providing a nanosized
ceramic powder to perform thereon a thermal analysis and thereby
attain an endothermic peak temperature (S101); (B) performing an
impurity-removal heat treatment on the nanosized ceramic powder at
a temperature higher than the endothermic peak temperature (S102);
(C) switching the nanosized ceramic powder from a temperature
environment of the impurity-removal heat treatment to an
environment of a temperature higher than a phase change temperature
of the nanosized ceramic powder, followed by performing a
calcination heat treatment on the nanosized ceramic powder in the
environment of the temperature higher than the phase change
temperature of the nanosized ceramic powder (S103), wherein the
nanosized ceramic powder skips the temperature environment between
the impurity-removal heat treatment and the calcination heat
treatment to shun generating a vermicular structure.
The present invention relates to a nanosized powder which exhibits
satisfactory sintering characteristics by undergoing an
impurity-removal process rapidly at high temperature. In an
embodiment of the present invention, the precipitation of the
starting nitrates (sources of Y, Al and Nd) is addressed and
described below. By introducing a precipitant and configuring
related parameters, such as the proportion of the precipitant, it
is feasible to adjust the pH and ion concentration of a gel
coprecipitate in an appropriate control solution to reduce
agglomeration of the gel coprecipitate, perform calcination by
two-stage nanosized powder pretreatment, effectively promote a
complete phase change procedure and control the particulate size,
and preclude powder aggregation which might otherwise occur as a
result of crystal overgrowth. Hence, the present invention retains
the uniqueness of the nanosized powder and renders it insusceptible
to abnormal growth.
An embodiment of the present invention includes the steps as
follows:
First, a nanosized YAG powder is prepared in two steps. In step 1,
the present invention uses an ammonium bicarbonate as a precipitant
and uses aluminium nitrate, yttrium nitrate and neodymium nitrate
as precursor salts. First, using aluminium nitrate, yttrium nitrate
and neodymium nitrate as precursor salts involves dissolving them
in deionized water according to the molar ratio, that is,
Nd:Y:Al=0.003:2.997:5, to produce 0.1-0.5 M of a YAG
(Y.sub.3Al.sub.5O.sub.12) aqueous solution, dissolving the ammonium
bicarbonate in deionized water to produce 0.4-3 M of a precipitant
aqueous solution, introducing the Nd:YAG aqueous solution, with a
medical intravenous drip infusion tube and a low constant infusion
flow rate of 1 ml/min, into the ammonium bicarbonate aqueous
solution, or pour the Nd:YAG aqueous solution into the ammonium
bicarbonate aqueous solution. In step 2, the ammonium bicarbonate
is dripped (or poured) into the Nd:YAG aqueous solution to
instantly produce a white precipitate, wherein the whole
precipitation process is accompanied by a blending process that
lasts 24 hours (but the present invention is not limited thereto)
until the reaction happens thoroughly. In step 3, a solid-state
powder precipitate is obtained by a centrifugal technique and a
repeated rinsing process performed with alcohol, and then the
solid-state powder precipitate is placed in an oven operating at
100.degree. C. (but the present invention is not limited thereto)
to undergo a drying process for 24 hours (but the present invention
is not limited thereto).
Second, the nanosized YAG powder undergoes a calcination process as
follows:
Referring to FIG. 2, there is shown a graph of DTA/TG of a
nanosized YAG powder of the present invention. As shown in FIG. 2,
according to the present invention, to prevent chemical residues
from affecting the sintering of the powder, it is necessary for the
starting precipitate to be analyzed with differential thermal
analysis (DTA)/thermogravimetric analysis (TG) in order to evaluate
the thermal behavior of the starting powder. As shown in FIG. 2,
the temperature rises at a rate of 10.degree. C. per minute. The
DTA curve shows two conspicuous endothermic peaks at 180.degree. C.
and 250.degree. C., respectively, and around 50% thermogravimetric
loss occurs at these temperatures, indicating that the chemical
residues decompose at these temperatures. Hence, in this
embodiment, the nanosized YAG powder undergoes preheat treatment at
300.degree. C. to get rid of most of its chemical residues and then
be placed in a pipe-shape furnace, which is already preheated to
reach temperatures of 1200.degree. C. and 1400.degree. C., to
undergo calcination for one hour.
Referring to FIG. 3, there are shown SEM pictures of the nanosized
YAG powder calcinated at 1200.degree. C. (picture a) and
1400.degree. C. (picture b) according to the present invention.
Referring to FIG. 4, there is shown a graph of the distribution of
particle diameters of the nanosized YAG powder calcinated according
to the present invention. Referring to FIG. 3, the phase change and
crystal growth taking place at 1200.degree. C. and 1400.degree. C.
occurs by a self-integration mechanism to thereby take less time
staying at a lower temperature, say <1100.degree. C., and thus
preclude a vermicular structure which might other arise from the
mutual sintering of crystals. At 1400.degree. C., since the
calcination temperature is high, the average particle diameter
reaches 445.6 nm, with a standard deviation of 63.3 nm. An analysis
of the powder particle diameters of a sample obtained when the
temperature-holding temperature decreases to 1200.degree. C.
indicates that the powder particle diameters decrease to between
200 nm and 350 nm, with an average particle diameter of 305.4 nm,
and the standard deviation decreases to 18 nm.
Comparison 1
Given the fact that YAG is a high-temperature product, YAG in a
single pure phase can be produced by a solid-state reaction only
when calcinated 1600.degree. C. for a sufficiently long
temperature-holding period of time. However, with all its reacting
ions being uniformly distributed at an atomic level, chemical
coprecipitation reduces greatly the temperature required for a
phase change. In the second stage, the temperature in a box furnace
rises at a rate of 10.degree. C. per minute to eventually reach
900-1200.degree. C. and then stay at 900-1200.degree. C. for one
hour. Afterward, the box furnace cools down spontaneously. All the
resultant products undergo XRD and SEM analysis. Referring to FIG.
5, there is shown an XRD spectrum of a powder sample obtained by
calcinating the nanosized YAG powder at 900-1200.degree. C. for one
hour according to the present invention. Referring to FIG. 6, there
are shown SEM pictures of a powder sample of the nanosized YAG
powder kept at 1100.degree. C. and 1200.degree. C. for one hour
according to the present invention, respectively. As revealed by
the SEM pictures, given a calcination temperature of
900-1000.degree. C., although the powder turns into YAG phase, YAM
phase remains unabated. It is only when the temperature increases
to 1100.degree. C. that the powder turns into a single phase YAG
completely, thereby indicating that this process technique requires
a high temperature of 1100.degree. C. or above in order to
effectuate a complete phase change. However, given a calcination
temperature of 1100.degree. C., the powder particle diameters are
mostly less than 100 nm, and a conspicuous vermicular structure
comes into being. When the temperature increases to 1200.degree.
C., not only do the powder particle diameters increase markedly,
but the particle diameters also fall substantially into the range
of 100-500 nm, not to mention that the vermicular structure is
dwindling, thereby indicating that a reduction in the time spent on
staying at a low temperature is effective in precluding the
vermicular structure which might otherwise arise from the mutual
sintering of crystals.
Comparison 2
Comparison 1 indicates that a conspicuous vermicular structure
forms by calcination at 1100.degree. C. for one hour, and that the
vermicular structure wanes as soon as the calcination temperature
rises to 1200.degree. C. Hence, Comparison 1 indicates that, at a
low temperature, crystal tends to grow by orientation attachment
and thus causes the vermicular structure. To bring a more desirable
calcination condition, Comparison 2 entails circumventing the
low-temperature heat treatment stage and directly conducting a
calcination quenching experiment on the coprecipitation products in
a pipe-shape furnace. The experiment of Comparison 2 involves
raising the temperature in the pipe-shape furnace in advance so
that attaining the temperature of 1400.degree. C. is immediately
followed by placing the coprecipitation powder in a pipe-shape
furnace, keeping the temperature for 15-60 minutes, and thereafter
removing the coprecipitation powder from the pipe-shape furnace so
as for the coprecipitation powder to undergo rapid quenching at
room temperature. Referring to FIG. 7, there is shown an XRD
spectrum of a coprecipitation product calcinated at 1400.degree. C.
for 15-60 minutes according to the present invention. Referring to
FIG. 8, there are shown SEM pictures of a powder which did not
undergo an impurity-removing process but underwent calcination at
1400.degree. C. for 15 minutes (picture a), 30 minutes (picture b)
and 60 minutes (picture c) according to the present invention. As
revealed by the SEM pictures, under the 1400.degree. C. high
temperature calcination condition, the powder turns into a single
phase YAG by just staying at 1400.degree. C. for 15 minutes,
indicating that the high-temperature process is effective in
enhancing phase change efficiency. By contrast, SEM observation
shows that although no conspicuous vermicular structure happens to
the powder produced under the aforesaid calcination condition,
there is severe sintering among the powder crystals (as shown in
FIG. 8), probably because the starting precipitates still contain
plenty of chemical residues, such as carbonates and nitrates, and
the chemical residues are likely to cause crystals to adhere to
each other, and in consequence the crystals get sintered quickly at
high temperature when subjected to a calcination process.
Although the present invention is disclosed above by embodiments to
illustrate the features and benefits of the present invention, the
embodiments are not restrictive of the essential technical features
of present invention. Any persons skilled in the art can make some
changes and modifications to the embodiments without departing from
the spirit and scope of the present invention. Accordingly, the
legal protection for the present invention should be defined by the
appended claims.
* * * * *